The search for causes of war has been the major concern of international relations scholars for centuries. One suspects that wars are caused by all manner of things. The interest here is in why wars come about. It might be that ideological differences make it impossible for nations to interpret actions which were intended as friendly in any but hostile terms, or that nations make mistakes about what other nations actually do, i.e., nations go to war due to factual or perceptual errors, or that nations are simply wrong in their judgements as to how other nations will respond to their actions. These last three sorts of causes might lead to war when no nation wishes it. It is this sort of political phenomenon that one finds puzzling and is addressed here.